Presenter: John Toole (Woods Hole Oceanographic Institution)

Description:
The vertical structure of subinertial variability is examined using full-depth horizontal velocity and vertical displacement observations derived from Ocean Observatory Initiative (OOI) Global Site moorings.  Vertical profiles are characterized through Empirical Orthogonal Function (EOF) decomposition and compared to theoretical modal predictions for the cases of flat and sloping bathymetry. OOI observations were obtained from mooring clusters at 4 deep-ocean sites: Argentine Basin (42˚ 58.9’ S, 42 ˚ 29.9’ W, water depth 5200 m), Southern Ocean (54 ˚ 28.1’ S, 89˚ 22.1’ W, 4800 m), Station Papa (50˚ 4.2’ N, 144˚ 47.9 W, 4219 m), and Irminger Sea (59˚ 58.5’ N, 39 ˚ 28.9’ W, 2800 m).  As no single OOI mooring in these clusters provides temperature, salinity and horizontal velocity information (T, S, U, V) over the full water column, observations from two or more moorings (separated by up to 40 km) are combined.  Depths greater than ~150-300 m at these sites were sampled by McLane Moored Profilers (MMP); in three of the four cases, two MMPs were utilized on the moorings.  Owing to instrument failures, only about two years of full-ocean-depth observations are available from each OOI site.   Ignoring the finite time span needed for the MMPs to profile the water column, TSUV data on pressure surfaces were low-pass filtered in time with a 10-d cutoff (greatly reducing the aliased tidal and near-inertial signals) and vertical displacements of neutral density profiles were derived relative to the time-averaged profiles (that also were used to derive the dynamical mode profiles).  Results from the OOI Global sites are contrasted with a parallel analysis of observations about the axis of the Gulf Stream where much of the subinertial variability is associated with the Stream meandering past the mooring.